Battle of Guandu

The Battle of Guandu was the decisive battle of the war between Cao Cao and Yuan Shao that took place in You Province in 200 AD. Fought on the Central Plains with the supply base of Wuchao as the key location, the battle turned out to be Cao Cao's finest triumph; Yuan Shao's army was supplied only by Wuchao, and since he had a huge army, he had a greater supply problem than Cao Cao. When Cao Cao's generals assaulted the base, Yuan Shao's army was doomed.

The Two Warlords
Cao Cao and Yuan Shao were childhood friends, indulging in music and hunting, much to the dismay of Cao Cao's uncle (who was disowned by Cao Song for decieving him about Cao Cao). Yuan Shao was born of a family of noble lineage that also included the future usurper Yuan Shu. Cao Cao's family were an unproven clan from You Province in northeastern China near the Korean border. However, Cao Cao rose to fame when he was made commander of the cavalry forces that fought in the Yellow Turban Campaign. With this triumph, Cao Cao was granted lands in Yu Province in Central China, while Yuan Shao kept all of northern China and the Central Plains. Yuan Shao and Cao Cao both helped to organize the campaign against Dong Zhuo in 189 AD, which resulted in a victory at Hulao Gate that resulted in Dong Zhuo's destruction of Luoyang and his retreat to Chang'an, where he was killed three years later by his general Lu Bu.

Tensions arise
However, the distance between the two warlords grew as both rose to power; Cao Cao conquered almost all of central China from the warlords Tao Qian, Liu Yan, Lu Bu, Liu Bei, Zhang Ji, and Bao Xin, while Yuan Shao took over the northernmost province of China, Qing, after the Battle of Yi Jing, where he decimated Gongsun Zan, in 199 AD. In hopes of melting the ice between themselves, Cao Cao attempted to have Yuan Shao made Minister of Works, but Yuan Shao was embarassed, as he coveted a higher rank, General-in-Chief. Cao Cao eventually made himself Minister of Works, but it became inevitable that the two warlords would fight for the Central Plains and northern China.

Preparations
Yuan Shao had his strategist Xun Yu write a letter containing a declaration of war to Cao Cao, which reportedly gave Cao Cao a headache, as he had inferior troops. Yuan Shao assisted a rebellion in Xu Province by Liu Bei, but Xu Huang brutally supressed it, and Liu Bei fled to Yuan Shao's ranks. Xu Huang took Liu Bei's brother Guan Yu as a prisoner of war and Cao Cao treated him immaculately, giving him his prized steed Red Hare. However, his intense loyalty to Liu Bei could not be shaken off, and he refused to defect; instead, he would return to Liu Bei once his obligation to Cao Cao would be fulfilled.

Meanwhile, Yuan Shao and his generals Yan Liang and Wen Chou raised an army of 200,000 crack troops who had been blooded by the war on Gongsun Zan, and they established a supply base at Wuchao that would be opened upon an emergency. This base was near Guandu Castle, Cao Cao's fortress that he guarded with 80,000 troops; his armies also defended Baima and Yanjin. These two forts were ably defended by Xiahou Dun and Zhang Liao, respectively.

Opening
There was at first a tense standoff. Cao Cao sent his son Cao Pi to defend Guandu Castle, Xu Huang to Baima, and Zhang Liao to Yanjin. His forces deployed in time for Yuan Shao's attack, with his two trusted generals Yan Liang and Wen Chou advancing. At Yanjin, Guan Yu, wielding his legendary Blue Dragon spear, cut down Yan Liang in one blow, and rode to Baima and killed Wen Chou. However, he noticed Liu Bei was on the battlefield, and retreated because he had reserved his right to withdraw once he fulfilled his debt.

Baima, Guandu, and Yanjin
Meanwhile, Cao Cao's forces defended their forts at Bai Ma and Yan Jin, with Yuan Tan, Yuan Shang, and Yuan Xi leading the assaults. Former Lu Bu generals Wei Xu and Song Xian were cut down in the battle by the rival army, but Cao Cao's army successfully defended these forts, with aid from Guan Yu, and upon losing most of his troops, Yuan Shao ordered the supply base at Wuchao to open its gates to supply the frontline units, who had prepared siege works in front of Guandu Castle; Lu Xiang had set up siege towers and rams at the gates.

Wuchao
With the opening of Wuchao on queue, Cao Cao ordered the obliteration of the supply base. Xiahou Dun, his cousin and right-hand man, took a unit and slew Chunyu Qiong, before setting fire to Yuan Shao's supplies. Yuan Shao's troops were starved of their provisions and generals Zhang He, Gao Lan, and Xu You defected immediately. Yuan Shao immediately retreated to his main camp.

Knockout Blow
With Wuchao destroyed, the units besieging Guandu retreated, and were slaughtered by Cao Cao's troops, led by Cao Pi. Cao Pi also defeated Yuan Xi's wife Zhen Ji in a duel, and Zhen Ji told him that her body and soul were his thereafter. Yuan Shao's troops fell back hard to defend their master, but were cut down in the thousands. Yuan Shao himself was wounded in the attack on his camp, and withdrew.

Aftermath
The Battle of Guandu was the battle that shattered Yuan Shao's power. Afterwards, Cao Cao, assisted by Zhang He, defeated the remnants of his army, and after Yuan Shao's death in 202 AD, destroyed the armies of his sons, who fought one another for control of the Yuan family. By 207 AD, all of Yuan Shao's former empire were in Cao Cao's hands.